Police spokeswoman Holly Joshi said, "We expect the best from the community" when the verdict is announced in Los Angeles Superior Court, where the trial was moved because of concerns that Mehserle couldn't get a fair trial in Alameda County due to the extensive publicity the case has received locally.

But Joshi also said, "We won't tolerate any violence or destruction of property," referring to violence and vandalism in Oakland in the weeks after Mehserle shot and killed Grant, a 22-year-old Hayward man, when he and other officers responded to a report of a fight on a train at the Fruitvale station in Oakland early on Jan. 1, 2009.

Mehserle's trial began last week and is expected to last a month.

"We're not expecting any violence, but we want to calm the fears of the business community and property owners," Joshi said.

Several hundred officers participated in the training session at the Port of Oakland today, she said.

In addition, Oakland Police Department leaders and other local law enforcement agency officials met at the Oakland Emergency Operations Center at 17th Street and Martin Luther King Way to practice coordinating their response to possible civil unrest, Joshi said.

Among the agencies that will be on call to help the Oakland Police Department in the event of any problems are the Alameda County Sheriff's Office, the California Highway Patrol and BART police.

Joshi said Oakland police also held a training session three weeks ago and plan to have another training session next week.

She said Mehserle's trial is "an emotionally-charged case" and extra officers will be on duty when there's a verdict.

Joshi said some community leaders are trying to defuse any negative reaction to a verdict by offering activities such as church services.

She said gyms and recreation centers will be open so people can get involved in recreational activities and there will be places where people can sing rap songs "to vent their emotions."